Inner groove distortion as tonearm moves toward the center of record What is cause??


What exactly produces INNER GROVE distortion??  

Is it a  poorly aligned cartridge, or a  mismatch between the cartridge and tonearm combo???  

Is this distortion more evident on budget tables, and/or tables under  $500??


Thank you,

S.J. 


sunnyjim
it’s just geometry and groove speed combined.

(1) in the inner grooves the stylus travels slower so there is less data to read so less information headroom. (2) with pivoting arms the inner grooves have slightly more non-linear distortion than at the null points. (3) the grooves curve sharper so they are relatively more ’pinched’, and (4) skating forces (related to centrifugal force) are stronger on the tone-arm.

a poorly aligned cartridge will certainly be more out of alignment on inner grooves. so there would be a multiplier effect on the inner groove nasties.

a cartridge not matched to the tonearm is not very relevant to the inner groove issue directly unless it won’t track the groove properly, then the inner grooves might make it worse. it could cause a skip. it depends on the nature of the incompatibility.

a linear tracking tonearm does theoretically eliminate the linear distortion, and longer pivoting tone arms have less geometric distortion; however; those tone arms must be perfectly set-up or they become worse than a relatively well set-up normal length pivoting arm.

so there are compromises with any approach and execution and precision of set-up typically rule the day.

regarding the investment in the tonearm and turntable and it’s effect on this question; it’s not irrelevant and effects ultimate performance and sometimes limits levels of precision set-up choices, but the basic principles still apply. there are not many really modest priced longer pivoting tone arms or linear trackers due to the higher costs of design and build.

less expensive turntables and arms have more noise and are less accurate in their speed so when that is combined with inner groove distortion it can tip the balance of musical enjoyment and that can be an issue. but normally that does not need to happen with a good set-up. i’ve not observed that being an issue. honestly it's been years since i spent time listening to $500 turntables, so i can't say much about them.
It's one of the reasons I now love digital music.
That, and the fact that I don't have to change the record every 30 or so minutes.
Sorry to intrude, but I just had to say it.
B
I would start by realigning your cartridge. Make it as perfect as you can with the tools you have. If that doesn't work, buy better alignment tools. 

Thanks to all who have responded so far. I appreciate your time

Special thanks to "mikelavigne" for a thorough explanation of the issues I posted. It was not overly technical, and very helpful in understanding the problems encountered  with vinyl playback and turntables. 

Can't put it any better than Mike L. A tangential tracker does make a significant improvement but there is still the slow speed which limits high frequency performance. This is where 45 RPM records shine. 
gdnrbob +1, I'm with ya!
In all of my experience with vinyl I don’t recall any issues with end of side distortion. Not even during the times of chronic audiophilia, not even with those extra long Bob Dylan LPs that couldn’t fit onto one side of a C90 cassette.

Even in the days of my Rega 3 with its silver S shaped arm I can’t recall any issues. Certainly not with the Ittok arm on my LP12. I think I would have done if there had been any as the final track on many of my favourite Beatles and Dylan LPs would be a standout one, played regularly.

I should add that I was careful with both cartridge alignment (gauges, mirror etc) and only ever used stylii which featured an elliptical profile. Back then we were told that a conical stylus could never track as well, so that was a big no-no.

Also the cartridges I used (Nagoaka and the better moving magnet Linn’s) were fairly easy to align. Tracking weight was always set within manufacturer’s given range, and finalised by listening carefully.

I also had an electronic Audio Technica stylus cleaner with its vibrating pad back then, which I can’t believe is not available today. It was pretty inexpensive but very effective, sadly I gave it away when I sold my Linn.
I remember doing tests even with a perfectly aligned Supex SD1000 in DV505 on Linn LP12, using 3 special CBS test records they sent us. 

I could even see on the oscilloscope with one of these CBS records of which one whole side is number of tracks all cut with the same amplitude 1khz sine waves, just so you could measure cartridge alignment distortion, the inner most groves had visually the worst "more" distortion than the others and the outer one was next worst, and if you can see it with your eye, believe me it's bad.
After that I was aware of it much more when playing music from then on, which really started to piss me off. Then thanks for a tangential arm Sony PSX800/XL55 Pro TT and MC I was much happier, then all changed again thanks to digital for coming along. 

Cheers George  
Who let those two digital guys in here. OFF with their heads!